HSU VTF-3 MK3 Turbo

The VTF-3 is the largest of the subwoofers in this roundup, especially when its optional Turbocharger attachment is installed. Removing the Turbo extension reduced maximum output about 2.3 dB from 25 to 62 Hz and 10 dB at 20 Hz, with no useful output at 16 Hz, and plugging one of the ports took the average output down another 2 dB. What sounded like internal suspension noise or port turbulence was often audible when the subwoofer was driven into overload during bass-limit testing, and with the crossover bypassed there was an out-of-band artifact at 250 Hz as well. With the Turbocharger attachment installed (the primary test mode) the VTF-3 MK3 does an honest 16 Hz — a rare feat. Crossover control frequencies matched dial makings more closely than is typical.

In the lab

Frequency response (at 0.5 meter)
Turbo: 24 to 92 Hz ±2.3 dB
Both ports open: 24 to 85 Hz ±1.6 dB
One port open: 26 to 85 Hz ±1.7 dB
Crossover bypass: 26 to 124 Hz ±1.9 dB

Bass limits, with Turbocharger (lowest frequency and maximum output with limit of 10% distortion at 2 meters in a large room)

Frequency	dB SPL
62 Hz	109
50 Hz	109
40 Hz	105
32 Hz	107
25 Hz	95
20 Hz	93
16 Hz	83

Average maximum output, 25 to 62 Hz: 105 dB SPL
Maximum output: 109 dB SPL at 50 Hz
Bass Limit: 16 Hz at 83 dB SPL

Crossover

Control Setting	Measured Frequency	Level Change
Bypass	124 Hz	–
90 Hz	92 Hz	-
60 Hz	60 Hz	+3 dB
40 Hz	37 Hz	-1 dB
30 Hz	36 Hz	-2.8 dB

Low-pass slope: 18 dB per octave

(Note: Reducing the crossover frequency also extended measured low-frequency response very slightly — about 2 Hz typically.)

Print

Stumble It